A human has a desire to communicate with somebody, and gain somebody's sympathy. The communication target in this case is not limited to a certain human, but may be all possible types of targets such as a machine and an animal. Up to the present time, various types of dialogue systems have been proposed as systems capable of realizing interaction between a human and a machine.
Patent Literature 1 is an example of such dialogue systems. According to a dialogue system disclosed in PTL 1, which is a system for realizing a smooth dialogue between a human and a machine, an ego-state estimating unit estimates an ego-state through transactional analysis (for example, Mineyasu SUGITA, “Transactional Analysis”, Nihon Bunka Kagakusya Co., Ltd., 1985), and a dialogue control unit outputs a response text based on the estimated ego-state.